I recently had this issue and was able to resolve it on Dell precision 9010's. The workstations had a working network driver but it was not the correct one when comparing it to the Dell driver list for the specific serial number. In my case i rebuilt the workstations from the ground up applying the drivers specific to the serial number for each system and then installing the anyconnect client. This resolved the issue and the anyconnect was able to successfully connect.
Prior to that i had tried many things, windows patches, cisco vpn profile xml file, several anyconnect versions, etc. and they all failed.
I hope this help anyone else who encounters this error.
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